Process and system for producing toner particles

Abstract

A process for producing toner particles, comprising polymerizing in an aqueous dispersion medium a polymerizable monomer composition containing at least a polymerizable monomer and a colorant, to form colored polymer particles, followed by washing and then dehydration to obtain toner particles, and feeding the toner particles into an inside-evacuatable and heatable container to make vacuum heat treatment while introducing into the container an injection medium having a temperature lower than glass transition temperature Tg of the toner particles and selected from the group consisting of i) saturated steam, ii) superheated steam and iii) high-humidity air having an enthalpy of 2,500 kJ/kg (dry air) or higher. Also disclosed is a system which carries out the above process.

What is claimed is:  
     
       1. A process for producing toner particles comprising: 
       polymerizing in an aqueous dispersion medium a polymerizable monomer composition containing at least a polymerizable monomer and a colorant, to form colored polymer particles, followed by washing and then dehydration to obtain toner particles;  
       feeding the toner particles into an evacuatable and heatable container to carry out vacuum heat treatment; and  
       conducting the vacuum heat treatment for the toner particles while introducing into the container an injection medium having a temperature lower than glass transition temperature Tg of the toner particles and selected from the group consisting of i) saturated steam, ii) superheated steam and iii) high-humidity air having an enthalpy of 2,500 kJ/kg (dry air) or higher, said injection medium being fed at a flow rate of from 0.01 m 3 /hr·kg (toner particles) to 0.5 m 3 /hr·kg (toner particles).  
     
     
       2. The process according to  claim 1 , wherein said high-humidity air has a water content of 50% or more. 
     
     
       3. The process according to  claim 1 , wherein said high-humidity air has a water content of 60% or more. 
     
     
       4. The process according to  claim 1 , wherein said high-humidity air has an enthalpy of 6,500 kJ/kg (dry air) or higher. 
     
     
       5. The process according to  claim 1 , wherein said high-humidity air has a water content of 50% or more and an enthalpy of 6,500 kJ/kg (dry air) or higher. 
     
     
       6. The process according to  claim 1 , wherein said high-humidity air has a water content of 60% or more and an enthalpy of 6,500 kJ/kg (dry air) or higher. 
     
     
       7. The process according to  claim 1 , wherein said high-humidity air has a water content of 80% or more and an enthalpy of 6,500 kJ/kg (dry air) or higher. 
     
     
       8. The process according to  claim 1 , wherein said injection medium is fed at a flow rate from 0.04 m 3 /hr·kg (toner particles) to 0.27 m 3 /hr·kg (toner particles). 
     
     
       9. The process according to  claim 1 , wherein said vacuum heat treatment is the step of removing a volatile component remaining in the toner particles. 
     
     
       10. The process according to  claim 9 , wherein said volatile component contains at least an unreacted polymerizable monomer. 
     
     
       11. The process according to  claim 1 , wherein said toner particles fed for the vacuum heat treatment have a water content of 3.0% or less. 
     
     
       12. The process according to  claim 1 , wherein said toner particles fed for the vacuum heat treatment have a water content of 1.0% or less. 
     
     
       13. The process according to  claim 1 , wherein preliminary heat treatment is made before the vacuum heat treatment to remove the aqueous dispersion medium. 
     
     
       14. The process according to  claim 13 , wherein said preliminary heat treatment is the step of heat-treating wet colored polymer particles while dispersing the particles in high-velocity hot-air streams and simultaneously forwarding the particles in parallel flow with respect to those streams. 
     
     
       15. The process according to  claim 13 , wherein in said preliminary heat treatment, after or at the same time the aqueous dispersion medium has been removed, said colored polymer particles are made to have a material temperature of from 30° C. to 60° C., and are subjected to the vacuum heat treatment as the particles are maintained at that temperature.